M20J Engine Baffling / What option is best?

[redbaron1982]

Hey, I'm having a small issue that I'd like to fix. It's not super urgent but it is important.

My CHTs are a bit high, 415F climbing, just under 400F cruising. I'd like to be below 400F all the time, and cruising under 380F. I did a Savvy flight test profile and fuel/ignition wise everything seems to be ok. So they high temps are most likely related to deficient cooling rather than timing or overly lean mixtures.

Here are a few pictures of how my baffling looks like now.

I'm trying to find the best option, I'm considering:

• Buying a roll of reinforced silicone and repairing it myself. Although the current baffling doesn't look terrible and I'm not sure where to start replacing it.
• Buying GeeBee (is it the same GeeBee we have in MS?) kit.
• Buying an original baffling kit.

At this point I'm inclined to buy GeeBee (https://www.csobeech.com/GeeBee.html) kit.

What's your opinion on this? Also, do you guys think it's possible to bring the temperatures down 20F, so I stay under 400F during the climb with trailing cowling flaps at 26x26 and under 380 while cruising, with closed cowl flaps?

[N201MKTurbo]

Your baffle seals look OK to me. if you are worried about the puckers, you can cut the seal where it puckers and it will lay flatter.

[dzeleski]

49 minutes ago, redbaron1982 said:

Hey, I'm having a small issue that I'd like to fix. It's not super urgent but it is important.

My CHTs are a bit high, 415F climbing, just under 400F cruising. I'd like to be below 400F all the time, and cruising under 380F. I did a Savvy flight test profile and fuel/ignition wise everything seems to be ok. So they high temps are most likely related to deficient cooling rather than timing or overly lean mixtures.

Here are a few pictures of how my baffling looks like now.

I'm trying to find the best option, I'm considering:

• Buying a roll of reinforced silicone and repairing it myself. Although the current baffling doesn't look terrible and I'm not sure where to start replacing it.
• Buying GeeBee (is it the same GeeBee we have in MS?) kit.
• Buying an original baffling kit.

At this point I'm inclined to buy GeeBee (https://www.csobeech.com/GeeBee.html) kit.

What's your opinion on this? Also, do you guys think it's possible to bring the temperatures down 20F, so I stay under 400F during the climb with trailing cowling flaps at 26x26 and under 380 while cruising, with closed cowl flaps?

What kind of CHT probes do you have? Do they go to the spark plugs or are they screwed into the cylinder head directly? The spark plug probes will run hotter then cylinder head probes.

Do you have a datalog from an engine monitor? What is your take off full rich fuel flow? And at what elevation + DA?

How do you have the engine configured for climb? Full rich? Prop full forward? Full throttle?

Check the baffles in between cylinders, make sure they are there. Last time I checked mine they were held in with springs and can easily be installed incorrectly.

[Niko182]

what type of cht probes do you have? and what instrument do you have to monitor the engine telemetry?

[redbaron1982]

The engine monitor is a GI 275, the CHT probes are screwed into the cylinder heads.

Regarding the power settings, I mentioned in my initial post that I climb at 26x26, but if you guys want more detail here is a link to the data in Savvy.

Savvy did analyze the info and they don't see any issue with the engine parameters, except it's running a bit hot.

[MikeOH]

I was happy with GeeBee’s baffles(not the same guy as the one who posts nowadays), but yours look good to me.

In summer my #2 CHT will hit 420 in a climb. However, cruise temps run in the low 300s with cowl flaps closed (65% LOP) M20F.

[Ragsf15e]

12 minutes ago, redbaron1982 said:

The engine monitor is a GI 275, the CHT probes are screwed into the cylinder heads.

Regarding the power settings, I mentioned in my initial post that I climb at 26x26, but if you guys want more detail here is a link to the data in Savvy.

Savvy did analyze the info and they don't see any issue with the engine parameters, except it's running a bit hot.

Those baffles look real nice.

What speed are you climbing at?

[Niko182]

Might also treat your chts better if you climb WOT full rpm

Edited May 4, 2023 by Niko182

[redbaron1982]

4 minutes ago, Ragsf15e said:

Those baffles look real nice.

What speed are you climbing at?

I was climbing at 500fpm, I think it was around 110kt but not sure.

[redbaron1982]

1 minute ago, Evan said:

Can you post your SAVY flight here? The link to it would be helpful.

Also, when your cowl flaps are closed do they trail a bit or is it fully shut? 

I did add it.

[Greg Ellis]

@Evan

https://apps.savvyaviation.com/beta/shared/flight/6853097/57d410e2-cfb6-4ab2-af3e-73fbea98b5bb

[Ragsf15e]

34 minutes ago, redbaron1982 said:

I was climbing at 500fpm, I think it was around 110kt but not sure.

The engine is very dependent on lots of airflow.  Your airspeed and your mixture is your cooling.  So cowl flaps should be full open in climb and measured to make sure they are properly adjusted.  Closed in cruise doesn’t mean they are flush.  The mm has the spec but they should be open around an inch when “closed”.  You need to climb at a higher speed than Vy.  110kts should do it.  This is key, so “not sure” isn’t what you want.  If you were at 100kts indicated, it would be noticeably hotter than 110kts.  I use 120mph since my airplane is in mph.

If you don’t like your climb cht, were you already full rich and still seeing 420cht?

[Ragsf15e]

Here’s a couple thoughts from the savvy graphic… it looks like just the start, taxi and climb portion, no?

So why is your egt climbing in your climb?  If you don’t touch the mixture, egt will fall slowly as you climb and get richer due to less air.  So to me, it looks like you’re too lean in the climb.

If you are leaning in the climb, you’re leaning too much.  Egt actual numbers aren’t exactly meaningful, but something in the low to mid 1200s in climb is more realistic.  You are in the mid 1300s.  Mine would be really hot too!

[redbaron1982]

Just now, Evan said:

A couple of questions after quickly looking at the savvy flight:

1. Are you leaning in the climb? 

2. There are some interesting oscillations in the #3 CHT starting at minute 41. Not sure what would cause this other than a failing probe or something flapping around.

I'd check the inter-cylinder baffles as well. 

I'm not leaning when I climb.

According to Savvy, the oscillating #3 CHT, could be a baffle giving way from time to time until it goes back to position. They said it is relatively common. Maybe that wrinkle that I have was flapping and generating the oscillation.

[GeeBee]

Just for clarification, you want GeeBee Aeroproducts, not me. If you get me, I will just take your money

https://www.csobeech.com/GeeBee.html

[Ragsf15e]

4 minutes ago, redbaron1982 said:

I'm not leaning when I climb.

According to Savvy, the oscillating #3 CHT, could be a baffle giving way from time to time until it goes back to position. They said it is relatively common. Maybe that wrinkle that I have was flapping and generating the oscillation.

I’m sure you could get all kinds of advice, but i’d go out and climb from sea level to 6k with all 3 knobs full forward, 115kts and cowl flaps full open.  I bet temps are fine.

If they aren’t, then at least you’ll have a good stable basis to analyze.

[MikeOH]

1 hour ago, Ragsf15e said:

Egt actual numbers aren’t exactly meaningful, but something in the low to mid 1200s in climb is more realistic.  You are in the mid 1300s.  Mine would be really hot too!

Hmm, you may have just provided a clue to my high CHTs!  My sea level full power EGTs are right around 1340. I wonder if my full power fuel flow is insufficient at 16 gph? My understanding of the RSA5 fuel injection system is that is NOT field adjustable.

What are others seeing for fuel flow on their IO360A1As?

[DCarlton]

13 minutes ago, MikeOH said:

Hmm, you may have just provided a clue to my high CHTs!  My sea level full power EGTs are right around 1340. I wonder if my full power fuel flow is insufficient at 16 gph? My understanding of the RSA5 fuel injection system is that is NOT field adjustable.

What are others seeing for fuel flow on their IO360A1As?

I need to look closely again next flight, but I think mine are right around 1340 too.  

[0TreeLemur]

Your takeoff fuel flow looks like it might be too low.  It should be closer to 20 gph when taking off near sea level.  In my J it is close to 20 gph and my CHT's are below 350.

[MikeOH]

3 minutes ago, 0TreeLemur said:

Your takeoff fuel flow looks like it might be too low.  It should be closer to 20 gph when taking off near sea level.  In my J it is close to 20 gph and my CHT's are below 350.

Yikes!

Does the J use the same engine/fuel servo as the F?

[PT20J]

At sea level my M20J IO-360-A3B6 runs between 18 and 19 gph at full rich, wot, 2700 rpm. 

Takeoff fuel flow is not field adjustable on a RSA servo. The fuel flow is a function of the airflow, but there are internal leakages can mess up the calibration. You might discuss it with Pete Nelson at Precision Airmotive (Precision makes the RSA injection system and Pete is the tech support person).

To check baffle seals, put a drop light through the oil door in the top cowling to illuminate the rear of the engine area and look through the cowling air inlets for light shining around the seals. If you think they are flopping around due to airflow, you can try poking them with a yardstick to see if they reverse direction and curl aft instead of forward which will let air bypass them.

New seals are available from: Guy Ginbey, Gee-Bee Aeroproducts, LLC, 800-556-3160, n77gb@msn.com

Skip

[Ragsf15e]

1 hour ago, MikeOH said:

Hmm, you may have just provided a clue to my high CHTs!  My sea level full power EGTs are right around 1340. I wonder if my full power fuel flow is insufficient at 16 gph? My understanding of the RSA5 fuel injection system is that is NOT field adjustable.

What are others seeing for fuel flow on their IO360A1As?

Yikes, mine is at 18.5gph on takeoff.  16 definitely seems low.

[0TreeLemur]

2 hours ago, MikeOH said:

Yikes!

Does the J use the same engine/fuel servo as the F?

Both are IO-360 with minor case differences.  Regarding fuel servo I don't know, probably the same I'd guess.  

From my experience with our C, I do know that the O-360 used in the C&G uses takeoff ff of 18 gph for 180 hp to keep the CHT's below 410.   Therefore, for 200 hp with the IO-360, the take off ff should be nearer to 20 gph.

[Niko182]

16 is way too low. However i didn't think of takeoff fuel flow because that still leaves him with the high CHTs during cruise.

[redbaron1982]

Mine depending on the day it fluctuates between mid 17's to 18's. When atmospheric pressure is high enough to get ~29in hg WOT I get 18.5Gph.